Hi 👋

I'm Marcel and I've been working as a freelance Senior Software Developer since 2010.

• TypeScript / JavaScript, Node.js, React.js, and related technologies

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TypeScript, GraphQL, Microservices, API, Frontend, Backend, Nest.js, Node, Swagger

I worked on many parts of the application, including a backend permission framework, data migrations, and complex frontend components.

Refactoring and test automation of social components.

JavaScript. Refactoring of a legacy code-base into testable code.

Node API and a React frontend with Material UI.

I helped create a process to automatically create configurable template-based PDFs with custom QR codes. I also implemented some interesting UI components like trees with drag and drop.

Next.js, AMP.

I helped the customer build a highly flexible and configurable input form library for their landing pages. I created components for the integration of a headless CMS including AMP pages and also added integration between lead capture pages and a new CRM system.

I helped one of the many project teams implement new features for an application that handles highly configurable forms for many of Volkswagen's markets. Complex, internationalized, large-scale API-driven React / Redux Application using Typescript, Atomic Design, a Pattern Library, and lots of interesting tooling. Also worked closely with Designers, UX, QA, and did lots of refactoring and code reviews.

Ported KnockoutJS application to React / MobX. Added a SOAP integration with an insurance company. Improved test coverage and development environment (Docker). Integrated payment gateway (SEPA, CC). Rails backend.

Kanban, Ruby on Rails, Swagger, ES6, jQuery, ReactJS, CSS, Coding best practices

Refactored codebase, improved test suite by decoupling domain logic from Rails framework, introduced JS tests, implemented new features, extracted service from a monolithic application. Worked with internationally distributed teams.

Scrum, Ruby on Rails, Swagger. Mostly backend.

I helped migrate their legacy, Perl-based, payment system to Ruby on Rails.

Scrum, Ruby, Rails, Javascript, jQuery, ReactJS, Refactoring, Code best practices

Implemented several Frontend features with ReactJS, refactored custom javascript widgets to React components, restored test suite, refactored code so it can be tested properly.

Scrum, Ruby on Rails, Refactoring, Code best practices

Implemented a new layout for a custom landing page in a complex system.

Ruby on Rails, AngularJS, Scrum, Code Reviews

Implemented parts of the backend configuration UI for their firewall system.

Scrum, Javascript, jQuery, AWS Lambda, Nodejs

I helped build the next incarnation of their personalized product recommendation application. This involved front- and backend as well as overall service architecture.

Refactoring and implementation of new features due to business model changes.

Data import, load tests, connect shop to external factoring service.

Maintenance, bug fixes

Event location lead engine. Improvement of lead quality. Scaling on Heroku. Ruby on Rails.

Ruby on Rails development, mostly maintenance, and refactoring. Fixed some infrastructure bottlenecks and implemented important sales-relevant features.

Mostly remote Ruby on Rails greenfield development. I implemented a crawler that monitors the websites of competitors for changes, takes screenshots, and so on. I also created a bookmarklet for the service so users can select parts of a website that they are most interested in monitoring. I used Couchbase, Redis, resque, RSpec, etc.

Onsite Ruby on Rails greenfield development in tech lead role. Used Heroku (later scalarium), Postgres, sphinx, chef, and various gems. Virtual currency item shop.

Remote Ruby on Rails development. Refactored test infrastructure and increased test coverage. Implemented backend and frontend features.

Onsite Ruby on Rails development. The main topics were backend features and test coverage.

Onsite Ruby on Rails development. I worked both on backend and frontend tasks. A lot of internationalization-related tasks and some frontend work. We used scrum.

Mostly remote Ruby on Rails development. Multi-tenant Whitelabel solution for health insurance companies. Hardware data graph representation. Mostly backend work.

Created a crawler framework that allowed text mining of job postings on various websites.